As Ireland
looks to the creation of a credible knowledge economy to substitute its ailing
manufacturing competitiveness, what better solution than to stimulate a cutting
edge research knowledge base while helping to exploit our regions untapped
renewable energy resources. The Atlantic waves that incessantly crash on
Ireland’s western shores are constantly dissipating energy. On average about
50GW of power, or 20 times the electrical power consumed by the entire Irish
grid, is dissipated uselessly as heat. If even 1% of this could be converted to
useful electricity, it could provide 20% of Ireland’s needs. A report produced
by ESBi and the Marine Institute has estimated that, allowing for technological
and accessibility limitations, about three quarters of the Irish electricity
requirements are potentially realisable, with a current market value of about
€2bn per annum. All of this can be achieved from an infrastructural deployment
that will have a small or positive environmental impact and will likely meet
minimal public resistance. If the development plan outlined by the Marine
Institute and Sustainable Energy Ireland is followed, it is estimated that wave
energy could be worth €270M to the Irish economy by 2020 and would only expand
after that with the global market estimated to be worth in the order of €50 to
€200bn. However, there are some technical hurdles and economic uncertainties
that need to be addressed before investors will feel safe backing this rosy
prospect. The trouble is that addressing such hurdles requires huge investment
in itself. Does Ireland have the courage to cough up the cash and fill that
funding gap?

The Irish Wave Energy Resource: Power diminishes closer to the coastline but in
the green band there is still 50kW for every metre of contour.

The
solar energy falling on our planet heats the atmosphere and converts some of the
solar power to wind energy. The wind in turn imparts some of its energy into
the oceans, where it is stored mechanically as wave energy. As the energy from
the sun trickles down through this sequence, its “intensity” is increased. In
Ireland, the average amount of solar energy incident with any square meter of
surface is only enough to light a few light bulbs. The energy available from
the wind passing through an imaginary vertical square meter is about three times
as much. In ocean waves however, there is on average over 2kW passing through
each square metre of ocean, plenty enough to power an entire home. The resource
might be impressive, but practical and affordable methods of converting this
chaotic form of energy into convenient electricity have so far been much more
illusive than for wind or solar energy.

The idea of
extracting useful energy from ocean waves has been tantalising inventors and
engineers ever since Stephen Salter of the University of Edinburgh highlighted
its true potential in “Wave Power” published in the scientific journal “Nature”
in 1974. Early pioneers of wave energy established the fundamental theories of
primary wave energy extraction, that is to say the scientific understanding of
how a physical interface with the ocean could extract the mechanical energy that
the ocean stores. “To absorb a wave is paradoxically to generate a wave”, the
very personable author on the subject, Prof Johannes Falnes, sternly reminded
the next generation of wave energy enthusiasts, gathered at a conference
celebrating his 75th birthday in Trondheim last December. Any
oscillating body bobbing in the sea is capable of generating a wave field
outwards across the sea surface. The trick is to radiate a wave field that
cancels out as much of the incident ocean waves as possible, thereby absorbing
the equivalent energy into the bobbing body. Falnes and his colleague Kjell
Budal at NTNU Trondheim discovered this “antenna effect”, where a floating
“point absorber” could theoretically absorb far more wave energy from the sea
than that which is directly incident upon its geometry, analogous to a radio
antennas ability to absorb radio waves. The upshot of this effect is that, in
order to absorb a maximum amount of wave energy, the body must be driven in an
oscillating “resonant” condition where it will absorb and store the energy from
the sea around. The body’s motion must then be controlled within practical
limitations, by introducing “power take off” (PTO) machinery which can deliver
this mechanical power to the electricity grid.

In a scaled
laboratory test in an Edinburgh wave tank, Stephen Salter managed to absorb over
90% of a regular wave using his famous “duck” floater. In the test, this
specially designed geometry pitched about a fixed central axis where an
electrical generator then converted the relative motion to electricity. Note in
Fig 2 that the circular orbits of wave particles on front of the duck device are
completely diminished behind the duck, indicating near total absorption of the
wave’s mechanical power.

A time exposure of Salter’s duck in motion in an Edinburgh laboratory wave
tank. Note the orbits of tracer fluid showing wave motion in front of the duck
to the right. This is completely diminished behind the duck. The power has
been completely absorbed.

At small
scale in a laboratory, an electric generator was directly able to absorb the
wave energy. However, one of the considerable difficulties is how to create
this power take off force at full scale and out in the open and often violent
Atlantic ocean. There are two main complications. Firstly, the force must be
reacted by the relative motion with a second body. This could simply be the
shoreline for on-shore devices, or a connection to the sea floor in shallower
water. An offshore device can also be “self-reacting”, for example by using two
floating bodies to react against each other as they move, or by using a large
weight inside the floating structure to react against. This requirement leads
to mechanical complexities and in some designs, an “end stop” problem where,
under extreme waves, the power take off machine must necessarily run out of
stroke, causing a bump and inducing large unpredictable loads in the structure.
Secondly, mechanical power is a product of force and speed. The nature of wave
power is one of very high forces and slow speeds. As well as the fact that high
forces require stronger structures, electrical generators also much prefer
higher speeds than waves naturally provide. Wind energy suffers the same
problem and requires very troublesome gearboxes that convert turbine windmill
speeds as low as 1 revolution every 5 seconds up to the electrical generator
shaft speeds 100 times faster.

There are a
number of methods being considered for this power take off application. Stephan
Salter decided that high pressure oil hydraulics was the preferred option,
similar to a digger bucket being used in reverse
(i.e. the waves wiggle the bucket!).
High pressure hydraulics can carry huge amounts of power with only relatively
small equipment compared to electrical motors and generators. Not content with
the efficiency of hydraulic machines available on the market, Salter led a team
at the University of Edinburgh to produce a highly efficient hydraulic machine.
They also found a way of providing the required reaction forces using the
gyroscopic forces of heavy spinning discs inside the device, the same force that
keeps a bicycle vertical. This can be sealed inside the device and has no “end
stop” problem.

An
Oscillating Water Column (OWC) using a Wells Turbine to convert wave energy to
electricity

Another power
take off option is to use air turbines. This is where entrapped air in a
chamber above the sea surface is compressed by the waves outside, causing
oscillating airflows through a turbine duct. The concept is called an
Oscillating Water Column (OWC). Such power will be familiar to anyone who has
listened to large waves entering partly submerged caves at the coast. The wells
turbine, invented by Prof. Wells of Queens University Belfast can be applied in
an OWC. A wells turbine is capable of extracting shaft power in a constant
rotational direction despite the oscillating airflow. Some designers tout the
relative simplicity of this solution and its ability to convert huge wave forces
at slow speeds into very fast shaft speeds for electricity generation. Others
however, highlight its inefficiency where an absolute maximum of 40% of the
available pneumatic power can be converted to shaft power. Efforts to improve
efficiency usually add considerable cost and complexity.

Another big
challenge for developers is how to bring the power they generate to the market.
The wave resource is often remote from large population centres where it is
required and where the electrical grid is strong enough to cope. Long submerged
electrical cables are an extra cost and can be a headache for grid managers.
Furthermore, though less variable than wind energy, the wave resource is still
variable and must be backed up by other energy sources on days when there are no
waves. This limits wave energy’s potential contribution to an isolated Irish
grid. However, such problems are not unique to wave power and other forms of
renewable energy have to contend with similar issues. Ireland has the advantage
that along its Atlantic coastline is a strong grid and sizable energy demand,
with the country’s largest power station at Moneypoint, only about 30 km from
the exposed Clare coastline. The variable delivery problem is also much
improved if the supply is connected to a single larger grid, such as a Britain
and Ireland grid for example. The stabilising influence of Britain’s nuclear
resources and power supply smoothing infrastructure could play a vital role in
increasing the renewable contribution from more isolated regions in Ireland and
Scotland.

The
challenges are therefore not insurmountable and development teams in Edinburgh
and elsewhere had achieved good success until the oil shocks of the early 1980’s
receded and interest and support for the UK wave energy programme dwindled.
“The requirement at the time was for a large scale energy source, competing with
nuclear power. Off the shelf technology at that time was not up to the task.
It was like the Wright brothers building a jumbo jet”, recalls Stephen Salter.
Once financial support was cut, development could not be sustained. All was not
in vain, however, and much of the hydraulics technology conceived at that time
is still being developed by a spin off company called Artemis, while wave tank
laboratory design also led to the creation of a company called Edinburgh
Designs. More recently, there is a resurgent interest in wave energy and new
developers as well as Stephen Salter himself have been picking up where they
left off.

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Facing commercial realities:

The funding
gap left a generation gap in the wave energy research community. This is
obvious at any European wave energy meeting today, where young enthusiastic
researchers and developers are to be seen mingling with their more mature and
invariably wiser colleagues. The new generation are making their mark,
however. They find themselves sitting on the fence between the existing
theoretical ideals and the commercial realities of the world around them.

Is there
really a market for this electricity? What future electricity price are we
competing with? Should we aim for maximum efficiency or should we concentrate
on demonstrating survivability and reliability first? What support can we count
on from the government? What assurances can we give investors in such a high
risk, long term venture? What regulatory bodies do we have to deal with? As the
new generation attempts to answer these questions, the deepening concern over
energy security and increasingly entrenched consensus on the need to act against
global climate change is providing some of the answers. The ability to talk the
commercial language, court investors and compromise on technical ideals is
starting to take effect.

Ocean Power
Delivery Ltd (OPD), set up by Richard Yemm, a former student of Stephen Salter,
is an Edinburgh based commercial company set up in 1998 that is developing the
Pelamis concept (see Fig). It is probably the most advanced commercial outfit
in wave energy, employing over 70 people. They received funding from a
consortium of private venture capital, including funding from energy giant
General Electric as well as some funding from the UK’s Carbon Trust. After a
successful demonstration of their full scale prototype at the European Marine
Energy Research Centre (EMEC) in Orkney, they were awarded their first
commercial contract to deploy 3 devices in a demonstration project in Portugal
in 2005. OPD’s strategy has been to use 100% 'available technology' and
system components that are available 'off the shelf' and introduce new
technology to improve efficiency only after reliability has been demonstrated.
‘Survivability before power capture efficiency…these two essentially conflicting
aspects are often approached from the other direction’ stresses Richard Yemm,
now the company’s managing director.

Ocean Power
Delivery’s “Pelamis” device. A snake-like self-reacting device with hydraulic
machinery to extract power at each of its joint

While OPD are continuing efforts
centred in Scotland, it is by no means a one horse race. Inverness based Wavegen,
recently acquired by German engineering firm Siemens, has been developing air
turbine technology for wave energy applications. Their turbines have been
tested at full scale in the Limpet oscillating water column (OWC) on the
Scottish island of Islay. Further afield, another experimental OWC has been
developed by Portuguese developers on the island of Pico in the Azores. AWS
Ocean Energy, now based in Inverness are hoping to commercialise a device called
the Archimedes Wave Swing (AWS). This fully submerged device with zero visual
impact was developed by a Dutch company, “Teamwork Technology”. It has already
been tested at full scale off the Portuguese coast. In Norway, a shore based
OWC was built as well as a shoreline tapered channel device where waves ramp up
and “overtop” into a raised reservoir before being let back to the sea through a
hydro turbine. In Denmark, a one quarter scale prototype of a floating
overtopping reservoir device called Wave Dragon has been deployed with plans to
build a full scale version off the Welsh coast. Uppsala University in Sweden
are experimenting with smaller devices with a unique linear electric generator
for power extraction. Although efforts have been concentrated in Europe,
numerous other ideas have been pursued around the globe, including in Japan and
North America. There are seemingly endless ideas for how best to extract ocean
wave energy and as yet there is no clear winner. Wind energy went through a
similar stage of development about 20 years ago before the 3 bladed horizontal
axis turbine, synonymous with wind energy today, was accepted as the industry
standard configuration.

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Irish efforts to date:

Efforts in
Ireland have also been significant. The Hydraulics and Maritime Research Centre
(HMRC) in Cork, recently bolstered by funding from the Marine Institute under
the “Blue Power” project now employs over 15 researchers and technicians. The
HMRC has been involved in European wave energy development since 1979 and are
leading members of the EU funded Co-ordinated Action on Ocean Energy (CAOE).
The HMRC has an “ocean basin” laboratory where scale models can be tested in
realistic ocean sea states. Many of the prominent international projects have
used the HMRC’s facilities and knowledge at some stage in their development.
The HMRC have also outlined a protocol for how wave energy devices should be
developed, which provides a useful guideline for developers and investors.
Queens University Belfast have an ongoing wave power research group and were
responsible for the development of a full scale shoreline OWC device called
”Limpet” on the Scottish island of Islay. They also have a shallow water wave
tank and are now concentrating on solutions to be deployed in near-shore
regimes. The University of Limerick’s Wave Energy Research Team (WERT), based
within the department of mechanical and aeronautical engineering have also
carried out world leading research on air turbines for wave energy
applications. Finevera Renewables, a publicly floated Irish investment company
dedicated to developing renewable energy has also taken a bet on wave energy.
It has acquired 100% of AquaEnergy, originally a Swedish developed technology
but now mostly operating in North America.

As well as
having a strong foothold in the knowledge of wave energy, Ireland’s policy
makers and financers have also been making noise of late. In 2002 Sustainable
Energy Ireland (SEI), in conjunction with the Marine Institute, published the
public consultation document on “Options for the Development of Wave Energy in
Ireland”. The document lays out three options going forward. The first one
aims to take all the risks necessary to ensure that Ireland becomes an all out
technological leader in the field and to be in a position to benefit from any
large export industry. The second is to ensure that Ireland will be in a
position to utilise wave energy while having a small core of exportable research
excellence. The third option is to play an observational role in international
developments and to simply “buy in” the fruits of foreign work. While the
public response generally favoured the first option, the result since then has
resembles more option 2. In 2005 a follow up document “Ocean Energy in Ireland”
has been rubber stamped by the Department of Communications, Marine and Natural
Resources. It outlines a more concrete commitment to wave energy with a 4 phase
strategy culminating in a competitive market readiness for large scale Irish
wave energy deployment by 2020. Ambitions of having over 2200 Irish jobs in
ocean energy by 2025 are also expressed. The report claims that the policy “could
also see Ireland positioned with the potential to become a world leader in the
manufacture and use of ocean energy systems.”

Phase 1 of
this plan has already been underway since 2005. This phase is “to support
national
developers of wave energy devices through concept validation, model design
optimisation and scale model testing.” SEI have been
able to make some R&D funding available to developers and the Marine Institute
have set up a wave energy test side off Spiddal in Galway Bay. This is a benign
site, sheltered by the Aran islands and is suitable for testing ¼ scale devices
in the sea. Two indigenous Irish prototype devices have already been deployed.
Wavebob, invented by Irish physicist William Dick, is a 2 body, self-reacting
buoy, floating largely underwater. Like OPD’s Pelamis, it uses hydraulics for
power take off. The developers are Clearpower Technology Ltd, based in Northern
Ireland where they are backed by the UK’s Carbon Trust, Ireland’s Marine
Institute and
Norwegian shipping and energy magnate Fred Olsen.
The scaled prototype was tested during 2005 at the Marine Institute’s test
site. A second device, the OE Buoy is being developed by Michael Whelan of
Ocean Energy Ltd in Cork. This device uses the oscillating water column concept
applied to a floating device where use is made of the relative motion of the
buoy and the entrapped air column. Because it is a floating device, it can be
deployed further offshore where the wave resource is much better then at the
shoreline. Their prototype was deployed at the Marine Institute test site since
autumn 2006, where it has successfully survived very severe weather.

¼ Scale Wavebob in position at the Galway Bay Test Site

Artists Impression of the OE Buoy. A ¼ scale device has been in Galway Bay
since Autumn 2006.

So it seems
that, in principle at least, wave energy is being taken seriously in Ireland and
there is consensus about its potential benefits to this country. The
opportunity to do with wave energy what Denmark did with wind energy is an
enticing prospect for any government. Wind energy related activities now make a
valuable contribution to the Danish economy and have created in excess of 20,000
Danish jobs. The trouble for wave energy, as it was for wind energy, is that in
the current economic climate it is not possible to compete directly against
conventional energy production. In order to be truly economically viable, wave
power will require an economy of scale with hundreds, if not thousands of
machines being deployed in “wave farms”. As this happens, it could be expected
that the rising prices of depleting gas resources could make wave power a very
attractive, if not a necessary, solution for powering Ireland’s economy. This
could especially be the case if Kyoto commitments prompt EU taxes to be levied
on carbon emissions from more conventional power production. As it is, the
short term return for wave energy technology development is almost non-existent
so private investors tend to shy away. Britain committed £50 million of public
money to wave and tidal energy, but this is a drop in the ocean compared to, for
example the £15 billion required to develop a nuclear power plant. The
relatively little public funding that is available tends to be diluted among
numerous projects with legitimate claim to fund their development. These
funding problems can be overcome with a “feed in tariff” such as that introduced
by Portugal, where successful projects initially get far above the market rate
for the delivery of ocean energy to the electricity grid. This can motivate
investors and is almost certainly the reason for Scottish based OPD having their
first commercial deployment in Portugal.

The success
of wave energy hinges on its perceived strategic benefit to the future of a
particular society. Isn’t the time ripe for Ireland to prove its metal in the
industrial world as a leader in technical innovation? Perhaps more importantly,
as one of the highest per capita energy consumers in the world and with an
enormous wave resource in our back yard, there is a moral duty on us to
contribute to this field. Surely we are not content to sit on our laurels and
simply hope that someone else will continue to solve impending problems for us?
The next phase in the Irish strategy will be to go to full scale ocean prototype
testing of one or more devices in the full rigour of the Atlantic. This is due
to begin from 2008 onwards. That will require resources far beyond lip
service. The ability to commit the very significant funding required for this
phase and then to deliver a successful test, will be a true measure of Ireland’s
ability to meet the wave energy challenge. One can only hope that the Irish
decision making community and investors have the courage, and that researchers
and engineers possesses the knowledge, to ensure that this island will stand to
harvest the rewards of a potential energy revolution.